Testing of the J-2X Augmented Spark Igniter (ASI) and Its Electronics

Reliable operation of the spark ignition system electronics in the J2X Augmented Spark Igniter (ASI) is imperative in assuring ASI ignition and subsequent Main Combustion Chamber (MCC) ignition events are reliable in the J2X Engine. Similar to the manrated J2 and RS25 engines, the J2X ignition system electronics are equipped with spark monitor outputs intended to indicate that the spark igniters are properly energized and sparking. To better understand anomalous spark monitor data collected on the J2X development engines at NASA Stennis Space Center (SSC), a comprehensive subsystem study of the engine's low and hightension spark ignition system electronics was conducted at NASA Marshall Space Flight Center (MSFC). Spark monitor output data were compared to more detailed spark diagnostics to determine if the spark monitor was an accurate indication of actual sparking events. In addition, ignition system electronics data were closely scrutinized for any indication of an electrical discharge in some location other than the firing tip of the spark igniter a problem not uncommon in the development of high voltage ignition systems

Examination of Annular-Electrode Spark Discharges in Flowing Oxygen - An Overview

A parametric study of annular spark gaps, pressures, and spark discharges in flowing oxygen gas was performed with a Champion spark exciter. The range of the pressure-distance product for the experiment is from approximately 50 torr-cm to 2500 torr-cm. Measurements of breakdown voltage qualitatively trend with Paschen's curve. Spark duration remained constant until the pressure-distance product exceeded 200 torr-cm, and then steadily increased. The mean spark energy increases linearly with the pressure-distance on a log-log plot indicating that a definite power relationship exists. The distribution of sparks at low energies and low pressures is not Gaussian and has no dominant peaks. Moderate and high spark energies are bimodal, with the dominant mode near 80 mJ. As pressure increases, dominant and secondary modes approach the same probability

Examination of Annular-Electrode Spark Discharges in Flowing Oxygen Experimental Nuances

Microsecond sparks and the resulting plume of hot gas/plasma were examined against a parametric pressure-distance matrix. Schlieren imaging is used to capture the spatial and temporal location of spark discharge exhaust for two milliseconds. Low pressure and larger gap widths created the largest size and intensity signal for the spark-affected plumes. Experimental exit-plume velocities trend well with analytic predictions using a mean pressure between the chamber and atmospheric conditions. Due to the quadratic relation of the annulus area and gap width, larger gap width velocities are more accurately represented by analytic predictions using atmospheric pressure as the larger exit area restricts the flow less. The same pressure adjustment, when applied to breakdown voltages, improves data alignment with Paschens Curve

A decade of Semantic Web research through the lenses of a mixed methods approach

The identification of research topics and trends is an important scientometric activity, as it can help guide the direction of future research. In the Semantic Web area, initially topic and trend detection was primarily performed through qualitative, top-down style approaches, that rely on expert knowledge. More recently, data-driven, bottom-up approaches have been proposed that offer a quantitative analysis of the evolution of a research domain. In this paper, we aim to provide a broader and more complete picture of Semantic Web topics and trends by adopting a mixed methods methodology, which allows for the combined use of both qualitative and quantitative approaches. Concretely, we build on a qualitative analysis of the main seminal papers, which adopt a top-down approach, and on quantitative results derived with three bottom-up data-driven approaches (Rexplore, Saffron, PoolParty), on a corpus of Semantic Web papers published between 2006 and 2015. In this process, we both use the latter for “fact-checking” on the former and also to derive key findings in relation to the strengths and weaknesses of top-down and bottom up approaches to research topic identification. Although we provide a detailed study on the past decade of Semantic Web research, the findings and the methodology are relevant not only for our community but beyond the area of the Semantic Web to other research fields as well

The Grizzly, September 28, 2017

Constitution Day Sparks Student Discussions of Free Speech • Chin Brings Sexy Bad Girl Haikus, Asian American Blues Poems and Elegies to Ursinus Reading • Next Year\u27s Study Abroad Application Opens on October 3rd • Armstrong Lecture Brings Columbia University Historian Dr. Joshua Batts to Berman Museum • Home is Where the Bear is • New Species Comes to Ursinus • Opinions: Consciousness Raising Can Combat Rape Culture on Campus; Is This Sufjan Stevens Song Gay or Just About God? • Student Workers of the SMC • Pair of Wins Put Bears in Good Positionhttps://digitalcommons.ursinus.edu/grizzlynews/1626/thumbnail.jp

The Grizzly, October 12, 2017

USAS Fights to In-source Ursinus Cleaning Staff • Ursinus Releases 2017 Annual Security and Fire Safety Report • Dr. April Carpenter and her Team of Students Challenge the Rest, Ice, Compression, Elevate Approach to Recovery • Several Uninvited Visitors Reported in Reimert Courtyard • Sustainability Week Brought Fall Fun to Ursinus • Digital Aid for Humanities • Opinions: Puerto Rico Deserves Federal Assistance after Maria; Meal Plan Options Should Include Opt-out Opportunity • Mid-season Check-in with Ursinus College Field Hockey • Bears Upset Blue Jays, Remain Atop CChttps://digitalcommons.ursinus.edu/grizzlynews/1628/thumbnail.jp

Precise Measurement of the b-Quark Fragmentation Function in Z0 Boson Decays

We have developed a new technique for inclusive reconstruction of the energy of B hadrons. The excellent efficiency and resolution of this technique allow us to make the most precise determination of the b-quark fragmentation function, using e[superscript +]e[superscript -]→Z[superscript 0] decays recorded in the SLAC Large Detector experiment. We compared our measurement with the predictions of a number of fragmentation models. We excluded several of these models and measured the average scaled energy of weakly decaying B hadrons to be 〈x[subscript B]〉 = 0.714±0.005(stat)±0.007(syst)±0.002 (model dependence).Istituto Nazionale di Fisica Nucleare of ItalyJapan-U.S. Cooperative Research Project on High Energy PhysicsDepartment of EnergyU.K. Particle Physics and Astronomy Research CouncilKorea Science and Engineering Foundatio

Arc-Heater Facility for Hot Hydrogen Exposure of Nuclear Thermal Rocket Materials

A hyper-thermal environment simulator is described for hot hydrogen exposure of nuclear thermal rocket material specimens and component development. This newly established testing capability uses a high-power, multi-gas, segmented arc-heater to produce high-temperature pressurized hydrogen flows representative of practical reactor core environments and is intended to serve. as a low cost test facility for the purpose of investigating and characterizing candidate fueUstructura1 materials and improving associated processing/fabrication techniques. Design and development efforts are thoroughly summarized, including thermal hydraulics analysis and simulation results, and facility operating characteristics are reported, as determined from a series of baseline performance mapping tests